The Coach had come under fire before for fielding a second-string side in the Europa League, so he was prepared for the criticism.

“We know the group is open, just as it was before, but now we must focus on raising our morale after this heavy defeat,” he said.

“I know that young players need time and they learn by making mistakes. Perhaps we made a few too many tonight and a great team like Atletico punished us for them.

“However, these are things players have to go through, as we need this experience to grow. Our project involves growing youngsters and I was always aware there was the risk of this inexperience leading to an embarrassing defeat.

“I take full responsibility for what happened, but if I squeeze the same 10-11 players dry without putting my faith in the rest of the squad, then I don't think we can stay at a certain level over time,” argued Guidolin.

“We have many internationals in the side, so it's very difficult to play the same lads in every fixture.”

Udinese are still joint top of the group with Atletico Madrid, but Celtic are now just two points behind them.

“Now the group is closing up and clearly I could rotate the squad less in the remaining two matches.

“We cannot afford to step on to the field with arrogance, but I think it was more timidity than arrogance tonight. We have to compliment Atletico Madrid, even if we gave them a helping hand.”

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